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VACUUM TYPE CONVERTER.

APPLICATION FILED nor. 1. m5.

CHUBB.

Patented Aug. 8, 1916.

R% W mm m N T 6 Ag LEWIS W. CHUBB, OF EDGEWOOD PARK, PENNSYLVANIA,ASSIGNOR To WESTINGHOUSE.

ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

y VACUUM-TYPE CONVERTER.

Specification of Letters Patent. I

Patented Aug. a, rare.

Application file'd October 7, 1915. Serial No. 54,558.

gheny and State of Pennsylvania, have invented a new and usefulImprovement in- Vacuum-Type Converters, of ,which the following is aspecification.

My invention relates to vacuum-type converters, and it has for itsobject to provide a device of the character indicated wherein thetemperature of the arc space and of the cathode may be maintained atany-desired figure and wherein, at the same time, desirableelectrostatic conditiong within the The single figure of theaccompanying drawing is a side. view,'partially in elevation andpartially in section, of a vacuumtype converterv embodying the preferredtype of my invention.

In the manufacture of vacuum-type converters, it is frequently desirablethat the containing receptacle be formed of metal in order to havesufficient strength to with stand the conditions of severe service.

\Vhen designing for operation under heavy loads, the material of thecathode should be in intimate contact with said metal wall in order thatits heat may be readily dissipated.

. I find that the negative electrostatic charge imparted to the wall ofa converter by having the cathode in contact therewith exerts a more orless harmful influence on the operation of the device. The power arefrequently transfers itself, wholly or in part, fromthe cathode properto the metal of or to mercury globules on the inner surface of thewalls, resulting in sudden and violent changes in the resistance andlength of the arc path and consequent disturbances in the equilibrium ofthesystem, itbeing mani-' festly difficult to electrically insulate thecathode from the container wall without interfering with the proper heatdissipation.

I propose to surround the entire arc space,

within the container from a point well above the active portions of theanodes to a point adjacent the surface of the cathode with a shield o'rskirt of conducting inaterial. Said shield is insulated from both theanodes and-the cathode and is maintained at such a high voltage withrespect to the cathode that the tendency of the power are to strikethereto is reduced to a minimum.

Referring to the accompanying drawing erably formed of vaporizablereconstructing material, such, for example, as mercury or suitableamalgams. Each of the anodes 2 and 3 may be provided with shieldingmembers 5, if desired. A cylindrical shield or skirt 6 is mounted withinthe container 1 and shields substantially the entire inner exposedsurface of the container. A source of unidirectional'voltage 7 isconnected between the shield 6 and the container -1 through acurrent-limiting device 8 to maintain said shield 6 at substantially themaxi mum positive potential of the anodes 2 and 3, the flow of an arcfrom the member 6 to the cathode 4 being limited by the device 8.

In the operation of the converter, there is ,no tendency for the mainpower arc to strike from the anodes 2 and 3 to the member 6 because ofthe small difference of potential therebetween, and said are isprevented by the shielding action of said member 6 from impinging uponthewall of container 1. The temperature of the cathode 4 is thusrendered subject to control in the ordinary manner, as by a' coolingbath 9, while the electrostatic conditions within the container are asfavorable as when employing an insulated cathode.

While I have shown my invention in its preferred form, it will beobvious to those skilled in the art that it is susceptible of variousminor changes and modifications without departing from the spiritthereof and I desire, therefore, that only such 11mitations shall beplaced thereupon as are im-' posed by the prior art or are specificallyset forth in the appended claims.

I claim as my invention: v 1. In a vacuum-type converter, thecombination with a casing, of an anode and a cathode therein, aconducting shield surrounding substantially the entire arc'paththerebetween,- and means for maintainlng a positive charge on saidshield.

2. In a vacuum-type converter, the combination with a casing, of aplurality of anodes and a cathode therein, a conducting shieldsurrounding substantially the entire arc path therebctween, and meansfor maintaining a positive charge on said shield.

3. In a vacuum-type converter, the com bination with a conductingcasing, of an anode and a cathode therein, said cathode being inintimate contact therewith, a conducting shield surroundingsubstantially the entire ar'c path, and means for maintaining anelectrostatic charge on said shield that is positive with respect tosaid cathode.

4. In a vacuum-type converter, the combination with a conducting casing,of a plurality of anodes and a cathode therein, said cathode being inintimate contact therewith,

a conducting shield surrounding substantially the entire arc path, andmeans for maintaining an electrostatic charge on said shield that ispositive with respect to said cathode.

5. In a vacuum-type converter, the combiv nation With a conductingcasing, of a cathode therein and in intimate contact therewith,'aplurality of anodes therein and insulated therefrom, a shielding memberfor each anode, a conducting shield surrounding all of said anodes andextending into proximity to said cathode, and means for imparting tosaid last mentioned shield a charge that is positive with respect tosaid cathode.

In testimony whereof, I have hereunto subscribed my name this 28th dayof Sept, 1915;

LEWIS W. cnnnn.

